The canning or bottling of beverages typically requires that empty beverage containers be shipped from a container manufacturer to the beverage manufacturer where they are filled using an automated filling machine. In the case of canned soft drinks and beer, the empty cans are ordinarily sent to the beverage manufacturer in large quantities, and are typically stacked on pallets for shipment. To facilitate shipment to the beverage manufacturer, it is common for layers of equal-height cans to be tightly packed on a pallet, with each layer of cans being covered with a separator sheet which provides a surface for a next layer of cans to be placed. This process is repeated until the desired number of cans is stacked on the pallet. The stack of cans is then covered with a top frame, which can be made of plastic, wood, or other materials, and the pallet of stacked cans is secured for shipment. When using separator sheets of this type, a typical pallet may contain as many as about 20 layers having 400 cans per layer, or 8000 cans.
The separator pads must be designed to allow uncomplicated palletizing and depalletizing of the cans while simultaneously preventing cans from slipping out from the stack and falling off the pallet. Furthermore, the material used must be suitable in terms of sanitation, flavor-producing agents, and durability. Separator pads have previously been made from a chipboard material containing cellulose materials and a binder. Because the cellulose-based material is porous, insects and moisture could enter the sheet and cause contamination. Additionally, the chipboard sheets were sometimes found to emit an undesired flavor into the unfilled cans which, once filled, ultimately changed the flavor of the product. The chipboard sheets were also easily damaged, thus limiting their useful life.
A reusable composite polymer-based sheet has since been designed to overcome the disadvantages associated with the chipboard separator sheets. Such a sheet is disclosed in U.S. Pat. No. 5,080,960, the disclosure of which is hereby incorporated by reference. The sheet described in that patent comprises a central core of high basis weight, nonwoven, spunbonded fabric which is coated with a polymer layer that is finely roughened during processing resulting in a sheet with a matte finish. To overcome several disadvantages of the prior art, including the chipboard sheets, the sheet was designed to be flexible yet shape retaining, tear-resistant, and otherwise durable. In addition, the sheet was designed to expedite the palletizing and depalletizing of the cans, allowing the cans to easily slide on and off the pallets, facilitating palletizing operations.
However, it has been found that as the can weight is decreased in order to lower costs, cans occasionally fall off during palletizing, shipment, depalletizing, and other times when the cans are moved.